1. Field of the Invention
The invention relates generally to the field of antilock braking systems. More specifically, the invention relates to the field of antilock braking systems for use with aircraft.
2. Description of the Related Art
Antilock braking systems have been employed for the past several decades to enhance braking efficiency of aircraft. Initially, such antilock braking systems included elaborate and expensive hydraulic controls that cycled the brakes on and off rapidly, and permitted the aircraft to be stopped with greater efficiency by preventing the wheels of the aircraft from slipping excessively or locking up. Electronic controls were later implemented and allowed for antilock action that is more responsive to actual ground conditions.
U.S. Pat. No. 3,880,475 to Booher discloses an antilock braking system consisting of a wheel speed transducer for each of the right and left wheels of the aircraft, a deceleration detection circuit, and a skid detector circuit. The speed transducers generate signals that are proportional in frequency to the wheel rotational velocity. A modulator circuit receives the outputs of the deceleration detector and skid detector circuits, and causes a control valve to regulate brake pressure in accordance with these signals. A logic circuit responsive to a locked wheel condition or a bounced landing is also included, and may temporarily override the normal control of the brakes.
U.S. Pat. No. 6,851,649 to Radford discloses an antilock braking system for use with aircraft and other vehicles. A speed sensor is associated with each wheel of the aircraft, and as the brake is applied to a wheel, the speed sensor measures the wheel speed and transmits this information to a processor. The processor then monitors the deceleration of the wheel, and compares this deceleration to a maximum allowable deceleration, which is a threshold above which the wheel would lock up and skid. If the deceleration of the wheel exceeds the maximum allowable deceleration, the processor transmits a signal to the brake causing the brake to release momentarily. Release of the wheel allows the wheel to momentarily rotate freely, thereby preventing wheel skids. The processor may also be configured to perform other routines, such as hydroplane protection operations.